题干

如图表示连接有电流表的一段神经纤维,且bc与cd的距离相等,下列说法错误的是(    )

A:刺激a点时,d点膜电位为外正内负

B:当兴奋从a点传至d点时,b点膜电位为内负外正

C:当兴奋从a点传至d点时,电流表发生两次方向相反的偏转

D:刺激c点时,电流表的指针发生偏转一次

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D

同类题3

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    At thirteen, I was diagnosed(诊断) with kind of attention disorder. It made school difficult for me. When everyone else in the class was focusing on tasks, I could not.

    In my first literature class, Mrs. Smith asked us to read a story and then write on it, all within 45 minutes. I raised my hand right away and said, “Mrs. Smith, you see, the doctor said I have attention problems. I might not be able to do it.”

    She glanced down at me through her glasses, “You are not different from your classmates, young man.”

    I tried, but I didn't finish the reading when the bell rang. I had to take it home. In the quietness of my bedroom, the story suddenly all became clear to me. It was about a blind person, Louis Braille. He lived in a time when the blind couldn't get much education. But Louis didn't give up. Instead, he invented a reading system of raised dots(点), which opened up a whole new world of knowledge to the blind.

    Wasn't I the “blind” in my class, being made to learn like the “sighted” students? My thoughts spilled out and my pen started to dance. I completed the task within 40 minutes. Indeed, I was no different from others; I just needed a quieter place. If Louis could find his way out of his problems, why should I ever give up?

    I didn't expect anything when I handled in my paper to Mrs. Smith, so it was quite a surprise when it came back to me the next day- with an “A” on it. At the bottom of the paper were these words: “See what you can do when you keep trying?”